Will 26" wheels make me slower?

No, but you will most likely look more appealing to the opposite sex. Seriously, ask yourself this: is a Formula 1 race car slower than a John Deere tractor? The tractor has bigger wheels, shouldn't it go faster? The answer obviously is that it does not. "Speed" has a lot to do with gearing, the tire width and pressure, and a lot to do with the engine. And yes, couples have successfully toured together -one on a 26" wheel and the other on a 700c wheeled bicycle – without ending up 23 miles apart by the end of the day. Your mileage may vary.